The tool-making industry manufactures a myriad of adapters for its tools. One known type of adapter is a universal joint adapter for use with socket wrenches. This known universal adapter typically includes: a handle portion and a socket portion. Each end portion includes a bifurcated or forked end yoke member with a pair of arms. A swivel block pivotally connects the handle and socket portions via each pair of arms. A spring surrounds the swivel block and the handle and socket portions. The spring encircling the end portions and swivel block permits a user to hold a socket wrench in alignment with a nut or bolt, for example, without having to re-apply the wrench to the object several times. Without the spring, the end portions of the universal joint would not be able to maintain a desired angle or be maintained in concentric alignment.
There are a number of known methods for coupling the ends of the spring to the end portions of the device. One known method is to provide an aperture in each end portion for receiving and securing an end of the spring. In this embodiment, each end of the spring is configured to define a projection which extends radially inward. The radially extending ends are sized and configured to be retained in the aperture of each end portion. In other words, each end of the spring terminates in the aperture in the end portions. In this embodiment, the interconnection of the spring and the end portion is difficult to terminate because the radially extending ends typically have to be pried out of the apertures to remove the spring from encircling the end members and the swivel block.
However, a spring coupled in this manner is not capable of providing simultaneous exertion of compression and tension forces on opposing sides of the handle and socket portions because the spring is only mounted at one point along the circumference of each end portion. A single point of contact can not simultaneously exert opposing compression and tension forces on opposite end portions. Accordingly, this method requires a spring having a substantially greater wire diameter (making the spring substantially stiffer) in order that the forces exerted by the spring at each single point of contact do not bias the device in a non-axially aligned manner. Such stiff springs are detrimental to the goal of flexibility of the device.
In a second embodiment for coupling the spring to the handle and socket portions, the spring is mounted in annular groves positioned in both the handle portion and the socket portion. This manner of coupling the spring to the handle and socket portions is disclosed in my U.S. Pat. No. 5,458,028, entitled "SOCKET WRENCH DEVICE", the entire disclosure of which is incorporated herein by reference. This patent discloses annular groves in the end portions having outer and inner lips or shoulders which define the inner and outer boundaries of the grooves within the socket and handle portions, respectively. By mounting the spring in this manner, the end portions are coaxially aligned in both tension and compression. However, machining such annular groves adds significant expense in manufacture, and these annular grooves do not permit the spring to be removed from the handle and socket portions in an easy manner. The difficulty in removing the spring can be remedied by double voids in the inner lip of a groove at one end of the device, as disclosed in my earlier patent. The purpose of the voids is to create a gap between the spring and the underlying lip or grove to facilitate removal and replacement of the spring. These voids may be obtained by machining away a portion of the outer surface of the lip. However, because of the orientation of the device as well as the location of the lip, machining the outer surface of the lip or groove is often a difficult machining operation, adding further manufacturing cost.
In response to the realized inadequacies of these known socket wrench devices, it became clear there is a need in the art for an easier and more economical manner of coupling the spring to the socket and handle portions of the device. This new socket wrench device must be capable of imparting both compression and tension forces to each yoke simultaneously and without slippage. Moreover, this new socket wrench device must permit the spring to be removed and replaced in an easy and economical manner.